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<H3>write_isurf command 
</H3>
<P><B>Syntax:</B>
</P>
<PRE>write_isurf group-ID Nx Ny Nz filename ablateID keyword args ... 
</PRE>
<UL><LI>group-ID = group ID for which grid cells store the implicit surfs 

<LI>Nx,Ny,Nz = grid cell extent of the grid cell group 

<LI>filename = name of file to write grid corner point info to 

<LI>ablateID = ID of the <A HREF = "fix_ablate.html">fix ablate</A> command which stores the corner points 

<LI>zero or more keyword/args pairs may be appended 

<LI>keyword = <I>precision</I> 

<PRE>  precision arg = int or double 
</PRE>

</UL>
<P><B>Examples:</B>
</P>
<PRE>write_isurf block 100 100 200 isurf.material.* ablation 
</PRE>
<P><B>Description:</B>
</P>
<P>Write a grid corner point file in binary format describing the current
corner point values which define the current set of implicit surface
elements.  See the <A HREF = "read_surf.html">read_isurf</A> command for a
definition of implicit surface elements and how they are defined from
grid conner point values.  The surface file can be used for later
input to a new simulation or for post-processing and visualization.
</P>
<P>The specified <I>group-ID</I> is the name of a grid cell group, as defined
by the <A HREF = "group.html">group grid</A> command, which contains a set of grid
cells, all of which are the same size, and which comprise a contiguous
3d array, with specified extent <I>Nx</I> by <I>Ny</I> by <I>Nz</I>.  These should be
the same parameters that were used by the <A HREF = "read_isurf.html">read_isurf</A>
command, when the original grid corner point values were read in and
used to define a set of implicit surface elements.  For 2d
simulations, <I>Nz</I> must be specified as 1, and the group must comprise
a 2d array of cells that is <I>Nx</I> by <I>Ny</I>.  These are the grid cells
that contain implicit surfaces.
</P>
<P>Similar to <A HREF = "dump.html">dump</A> files, the <I>filename</I> can contain a "*"
wildcard character.  The "*" character is replaced with the current
timestep value.  For example isurf.material.0 or
isurf.material.100000.
</P>
<P>The specified <I>ablateID</I> is the fix ID of a <A HREF = "fix_ablate.html">fix
ablate</A> command which has been previously specified in
the input script for use with the <A HREF = "read_isurf.html">read_isurf</A> command
and (optionally) to perform ablation during a simulation.  It stores
the grid corner point values for each grid cell.
</P>
<P>The output file is written in the same binary format as the
<A HREF = "read_isurf.html">read_isurf</A> command reads in.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "read_isurf.html">read_isurf</A>
</P>
<P><B>Default:</B>
</P>
<P>The optional keyword default is precision double.
</P>
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